This study is directed towards obtaining data from experimental animal systems (mouse) that will facilitate the use of islet transplantation in Man to reserve insulin dependent diabetes. The study will investigate: 1) The possibility of using in vitro recipient T cell activation to determine the immunogenicity of allogeneic islet tissue after varying periods of organs culture, and correlate these findings with subsequent transplant survival. 2) Use the passive transfer of graft specific T cells and antibody to determine the cellular and humoral factors that can damage or protect an established islet allograft. 3) Investigate the possibility of using organ culture to facilitate xenogeneic transplantation of functional islet tissue to non-immunosuppressed recipients.